Long COVID facts and findings: a large-scale online survey in 74,075 Chinese participants, 2024, Qin et al

[Nightsong]

Background
Research on long COVID in China is limited, particularly in terms of large-sample epidemiological data and the effects of recent SARS-CoV-2 sub-variants. China provides an ideal study environment owing to its large infection base, high vaccine coverage, and stringent pre-pandemic measures.

Methods
This retrospective study used an online questionnaire to investigate SARS-CoV-2 infection status and long COVID symptoms among 74,075 Chinese residents over one year. The relationships between baseline characteristics, vaccination status, pathogenic infection, and long COVID were analyzed using multinomial logistic regression, and propensity matching.

Findings
Analysis of 68,200 valid responses revealed that the most frequent long COVID symptoms include fatigue (30.53%), memory decline (27.93%), decreased exercise ability (18.29%), and brain fog (16.87%). These symptoms were less prevalent among those infected only once: fatigue (24.85%), memory decline (18.11%), and decreased exercise ability (12.52%), etc. Women were more likely to experience long COVID, with symptoms varying by age group, except for sleep disorders and muscle/joint pain, which were more common in older individuals. Northern China exhibits a higher prevalence of long COVID, potentially linked to temperature gradients. Risk factors included underlying diseases, alcohol consumption, smoking, and the severity of acute infection (OR > 1, FDR < 0.05). Reinfection was associated with milder symptoms but led to a higher incidence and severity of long COVID (OR > 1, FDR < 0.05). Vaccination, particularly multiple boosters, significantly reduced long-term symptoms by 30%–70% (OR < 1, FDR < 0.05). COVID-19 participants also self-reported more bacterial, influenza and mycoplasma infections, and 8%–10% of patients felt SARS-CoV-2-induced chronic diseases.

Interpretation
This survey provides valuable insights into long COVID situation among Chinese residents, with 10%–30% (including repeated infection) reporting symptoms. Monitoring at-risk individuals based on identified risk factors is essential for public health efforts.

Link | PDF (The Lancet Regional Health)
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Also a comment from Ziyad al-Aly - "Long Covid is a significant health crisis in China too" - Link | PDF

 

[Yann04]

10-30% of the population reporting Long COVID is a really high number given this has a sample size of 74’000.

To compare I think it’s something like 5-7% in the US.

 

[EndME]

10-30% of the population reporting Long COVID is a really high number given this has a sample size of 74’000.

To compare I think it’s something like 5-7% in the US.

Which probably just shows how meaningless such studies are...

 

[Eleanor]

Probably not a representative sample, if people experiencing long-term symptoms are more likely to take the survey?

 

[Yann04]

Probably not a representative sample, if people experiencing long-term symptoms are more likely to take the survey?

I think it was a general take it after you’re infected survey but maybe. I don’t have the energy to fully read sadly.

 

[EndME]

I think it was a general take it after you’re infected survey but maybe. I don’t have the energy to fully read sadly.

I think many can reasonably argue that a "general take a survey and see results" study can only meaningfully exist if it doesn't suffer from recruitment bias. I think one would have to understand how this referal system used in the study would work, but I doubt it is worth the effort as the study carries 0 insights and we have already seen similar studies for 4+ years that haven't moved the needle.